Or you can set permissions as an octal number. The permission bits have the meaning specified as in the description for umask below, except that a bit is set in order to give rather than deny permissions.For example, "chmod 640 file..." would set the file(s) to read and write (but not execute) permission for the user, read permission for group, and no permission for anyone else. This is represented as "rw-r-----" by the "ls -l" command.

What is the advantage of HASH table?Ans:-The major advantage of a hash table is its speed. Because the hash function is to take a range of key values and transform them into index values in such a way that the key values are distributed randomly across all the indices of a hash table

How to backup AIX server?Ans:-(1)For backup of rootvg, mksysb command can be used on command line or via smitty.Advantage of mksysb is that it can create a \'bootable\' media of the backup of rootvg.(2) For backup of filesystems, \'backup\' command can be used ( restore command to be used for restoration of the backup).(3) The answer given regarding savevg ( and restvg ) is correct.